X-ray computed tomography (CT) is a non-destructive technique for inspecting and analyzing internal structures of objects. In general, x-rays are absorbed or scattered as the x-rays travel through the objects. The x-rays not absorbed or scattered away are then detected by a detector system. The image formed at the detector system is known as an x-ray projection. Tomographic volume data sets are then reconstructed from a series of these projections as the objects are scanned at different angles via standard CT reconstruction algorithms.
For most X-ray CT microscopy tasks, the preferred source would be a synchrotron. These devices can produce bright, monochromatic, and collimated beams of radiation. Generally, such beam characteristics are ideal for CT microscopy. Synchrotrons are expensive and access to hemlines is often limited, however.
On the other hand, laboratory sources are more common and are lower in cost. Unfortunately, such sources produce beams that are cone-shaped, less bright and have relatively broadband spectral emissions, which include Bremsstrahlung background and characteristic emission lines. Moreover, there is usually a tradeoff between beam brightness and collimation.